Design for 3D Printed Tools: Mechanical Material Properties for Direct Polymer Additive Tooling.

In relation to the fourth industrial revolution, traditional manufacturing methods cannot serve the flexibility demands related to mass customization and small series production. Rapid tooling provided by generative manufacturing has been suggested recently in the context of metal forming. Due to the high loads applied during processes to such tooling, a purposeful mechanical description of the additively manufactured (AM) materials is crucial. Until now, a comprehensive characterization approach for AM polymers is required to allow a sophisticated layout of rapid tooling. In detail, information on compressive and flexural mechanical properties of solid infilled materials made by additive manufacturing are sparsely available. These elementary mechanical properties are evaluated in the present study. They result from material specimens additively manufactured in the fused filament fabrication (FFF) process. The design of the experiments reveals significant influences of the polymer and the layer height on the resulting flexural and compressive strength and modulus as well as density, hardness, and surface roughness. As a case study, these findings are applied to a cup drawing operation based on the strongest and weakest material and parameter combination. The obtained data and results are intended to guide future applications of direct polymer additive tooling. The presented case study illustrates such an application and shows the range of manufacturing quality achievable within the materials and user settings for 3D printing.

Development of Validated Methods and Quantification of Curcuminoids and Curcumin Metabolites and Their Pharmacokinetic Study of Oral Administration of Complete Natural Turmeric Formulation (Cureit™) in Human Plasma via UPLC/ESI-Q-TOF-MS Spectrometry.

Specific and sensitive ultra-high performance liquid chromatography-quadrupole time of flight-mass spectroscopy (UPLC-QTOF-MS) methods have been developed for the determination of curcuminoids and curcumin metabolites in human blood plasma. The UPLC-QTOF-MS method used a binary solvent delivery system and the chromatographic separation was performed on a C-18 (2.1 × 50 mm; 1.7 µm) column. Mass spectra were obtained on a Waters Xevo G2S Q-TOF mass spectrometer. The developed methods to characterize the pharmacokinetics of curcuminoids and curcumin metabolites in human blood plasma after an oral administration of bioavailable curcumin-Cureit™-were validated. It was found that the complete turmeric matrix enhances the concentration of tetrahydrocurcumin (THC), hexahydrocurcumin (HHC), octahydrocurcumin (OHC), curcumin-O-glucuronide (COG) and curcumin-O-sulfate (COS) in the blood plasma once the product is administrated.

1,3-disubstituted 4-aminopiperidines as useful tools in the optimization of the 2-aminobenzo[a]quinolizine dipeptidyl peptidase IV inhibitors.

In a search for novel DPP-IV inhibitors, 2-aminobenzo[a]quinolizines were identified as submicromolar HTS hits. Due to the difficult synthetic access to this compound class, 1,3-disubstituted 4-aminopiperidines were used as model compounds for optimization. The developed synthetic methodology and the SAR could be transferred to the 2-aminobenzo[a]quinolizine series, leading to highly active DPP-IV inhibitors.

Endothelin-converting enzyme-1 inhibition and growth of human glioblastoma cells.

Endothelin-1 (ET-1) is mitogenic and/or antiapoptotic in human cancers, and antagonists to ET-1 receptors are under evaluation for cancer treatment. Inhibition of ET-1 activation by the endothelin-converting enzymes 1(a)(-)(d) (ECE-1(a)(-)(d); EC 3.4.24.71) represents another approach to block the ET-1 effect in cancer. To evaluate this potential, we synthesized and characterized a series of low nanomolar nonpeptidic thiol-containing ECE-1 inhibitors, and evaluated their effect, as well as the effect of inhibitors for the related metalloproteases neprilysin (NEP; EC 3.4.24.11) and angiotensin-converting enzyme (ACE; EC 3.4.15.1), on human glioblastoma cell growth. Only ECE-1 inhibitors inhibited DNA synthesis by human glioblastoma cells. Exogenous addition of ET-1 or bigET-1 to glioblastoma cells did not counterbalance the growth inhibition elicited by ECE-1 inhibitors, suggesting that ECE-1 inhibitors block the proliferation of human glioblastoma cells most likely via a mechanism not involving extracellular production of ET-1. This class of molecules may thus represent novel therapeutic agents for the potential treatment of human cancer.

Structural basis of proline-specific exopeptidase activity as observed in human dipeptidyl peptidase-IV.

Inhibition of dipeptidyl peptidase IV (DPP-IV), the main glucagon-like peptide 1 (GLP1)-degrading enzyme, has been proposed for the treatment of type II diabetes. We expressed and purified the ectodomain of human DPP-IV in Pichia pastoris and determined the X-ray structure at 2.1 A resolution. The enzyme consists of two domains, the catalytic domain, with an alpha/beta hydrolase fold, and a beta propeller domain with an 8-fold repeat of a four-strand beta sheet motif. The beta propeller domain contributes two important functions to the molecule that have not been reported for such structures, an extra beta sheet motif that forms part of the dimerization interface and an additional short helix with a double Glu sequence motif. The Glu motif provides recognition and a binding site for the N terminus of the substrates, as revealed by the complex structure with diprotin A, a substrate with low turnover that is trapped in the tetrahedral intermediate of the reaction in the crystal.

Endothelin-converting enzyme inhibition ameliorates angiotensin II-induced cardiac damage.

We tested the hypothesis that endothelin-converting enzyme (ECE) inhibition ameliorates end-organ damage in rats harboring both human renin and human angiotensinogen genes (dTGR). Hypertension develops in the animals, and they die by age 7 weeks of heart and kidney failure. Three groups were studied: dTGR (n=12) receiving vehicle, dTGR receiving ECE inhibitor (RO0687629; 30 mg/kg by gavage; n=10), and Sprague-Dawley control rats (SD; n=10) receiving vehicle, all after week 4, with euthanasia at week 7. Systolic blood pressure was not reduced by ECE inhibitor compared with dTGR (205+/-6 versus 206+/-6 mm Hg at week 7, respectively). In contrast, ECE inhibitor treatment significantly reduced mortality rate to 20% (2 of 10), whereas untreated dTGR had a 52% mortality rate (7 of 12). ECE inhibitor treatment ameliorated cardiac damage and reduced left ventricular ECE activity below SD levels. Echocardiography at week 7 showed reduced cardiac hypertrophy (4.8+/-0.2 versus 5.7+/-0.2 mg/g, P<0.01) and increased left ventricular cavity diameter (5.5+/-0.3 versus 3.1+/-0.1 mm, P<0.001) and filling volume (0.42+/-0.04 versus 0.16+/-0.06 mL, P<0.05) after ECE inhibitor compared with untreated dTGR. ECE inhibitor treatment also reduced cardiac fibrosis, tissue factor expression, left ventricular basic fibroblast growth factor mRNA levels, and immunostaining in the vessel wall, independent of high blood pressure. In contrast, the ECE inhibitor treatment showed no renoprotective effect. These data are the first to show that ECE inhibition reduces angiotensin II-induced cardiac damage.

An immunohistochemical study of endothelin-1 converting enzyme in the human eye.

PURPOSE: The important role of ET-1 in vasoconstriction has been shown for the vasoregulation in the retina, choroid and optic nerve. ET-1 induced vaso-constriction, however, can be treated effectively at the level of endothelin-1 converting enzyme (ECE-1) by ECE-1 inhibitors because ECE-1 converts biologically almost inactive big endothelin to endothelin-1 (ET-1), the most potent vasoconstrictor known. The purpose of this study was to clarify the anatomical distribution of ECE-1 in the human eye. METHODS: 11 post-mortem eyes were fixed in 4% formalin and embedded in paraffin. 4 microm thin sections were analyzed immuno-histochemically using a self-produced monoclonal primary antibody against human ECE-1 and a polyclonal alpha-actin antibody for comparison. RESULTS: ECE-1 -IR was demonstrated in the corneal epithelium, vascular smooth muscle and endothelial cells, and in the non-vascular smooth muscle cells of the ciliary body, the dilator and sphincter muscle of the iris. CONCLUSIONS: A strong immunoreactivity for ECE-1 can be found in the blood vessels of the retina, optic nerve and choroid. Therefore, it should be possible to treat ET-1-induced vaso-constriction in the eye using ECE-1 inhibitors, especially in diseases like hypertensive vasculopathy, vasospasm, vaso-occlusions or low tension glaucoma.

Synthesis of triazole-Tethered pyrrolidine libraries: novel ECE inhibitors.

The solid-phase synthesis of substituted 1,2,4-triazoles tethered to a 4-mercaptopyrrolidine core 1 is described. This novel class of non-peptidic, Zn(2+) metallo-protease inhibitors was found to have inhibitory activity for the endothelin converting enzyme (ECE-1). The SAR of the substitution pattern in 1 is discussed.

Role of endothelin in mediating neurogenic plasma extravasation in rat dura mater.

In addition to their potent vasoconstrictor properties, the endothelins (endothelin-1 and -3) may possess neurotransmitter/neuromediator and neuroendocrine actions. The aim of the present study was to evaluate the role of endothelins (ET) in mediating neurogenic inflammation of cephalic tissues in the rat. For this purpose, bosentan, a specific non-peptide mixed antagonist of ET receptors, was tested in rat models of neurogenic and non-neurogenic plasma extravasation in the dura mater and extracranial tissues (eyelid, conjunctiva, lip, tongue). Bosentan was effective for preventing neurogenic inflammation in the dura mater induced by unilateral electrical stimulation of the trigeminal ganglion or intravenous injection of capsaicin, whereas it was ineffective in extracranial tissues or after injection of substance P (non-neurogenic inflammation). The effect of nerve fiber stimulation on ET plasma concentrations in superior sagittal sinus was measured using selective radioimmunoassays for ET-1 and -3. Endothelin-3 concentration significantly increased after intravenous injection of capsaicin, whereas ET-1 levels remained unchanged. Competition binding assays on microsomal membranes from the trigeminal ganglion revealed a single class of binding sites with equal affinity for ET-1 and ET-3, suggesting a homogenous population of ETB receptors. The role of ETB receptors in mediating inflammation was evidenced by the lack of efficacy of a selective ETA receptor antagonist, in contrast to the full efficacy of a selective ETB receptor antagonist, for preventing neurogenic inflammation induced by unilateral stimulation of the trigeminal ganglion. The role of ETB receptors was finally confirmed by the observation that exogenous administration of the ETB receptor agonist sarafotoxin S6c also induced plasma protein extravasation in the dura mater. This extravasation was not a direct effect of ETB receptor stimulation, because it was inhibited by spantide, a selective tachykinin receptor antagonist. These data strongly suggest that ET, acting through ETB receptors, may play an important role in mediating neurogenic inflammation in the meninges of rats. Since the profile of activity of bosentan is similar to that of the 5-HT1D/B agonists, sumatriptan and ergot alkaloids, one may speculate that ET receptor antagonists might be potentially effective in the treatment of acute migraine attacks.